Maths, but not as you know it…
Episode 10 of Tom Rocks Maths on Oxide Radio sees the conclusion of the million-dollar Millennium Problem series with the Hodge Conjecture, a mischievously difficult number puzzle, and the answer to the question on everyone’s lips: how many people have died watching the video of Justin Bieber’s Despacito? Plus, the usual great music from the Prodigy, the Hives and Weezer.
Image credit: Lou Stejskal
The first 3 articles from my Millennium Problems series have been published in Cambridge University’s Eureka Magazine – one of the oldest recreational mathematics magazines in the world, with authors including: Nobel Laureate Paul Dirac, Fields Medallist Timothy Gowers, as well as Martin Gardner, Stephen Hawking, Paul Erdös, John Conway, Roger Penrose and Ian Stewart. To say I’m excited would be an understatement… (pages 82-84 in case you’re interested).
Tom Rocks Maths is back on Oxide Radio for Hilary Term 2019 with the usual eclectic mix of maths and music. Learn more about the only million-dollar Millennium Problem that’s been solved so far, fun facts about the number 6, and a nursery rhyme themed puzzle. Plus, music from Bring me the Horizon, Queen and Papa Roach. This is maths, but not as you know it…
Sir Michael Atiyah explains his proof of the infamous Riemann Hypothesis in one slide. Recorded live at the Heidelberg Laureate Forum 2018.
A leading Millennium Prize Problem is the Navier-Stokes equation, which, if solved, could model the flow of any fluid – that means how aeroplanes navigate the skies, how water meanders in a river and how the flow of blood courses through your blood vessels… Understanding these equations in more detail will lead to scientific advances in all of these fields: better aircraft design, improved flood defences, and better drug delivery in the body. Fluids expert and mathematician Keith Moffatt took me down to the deep dark depths of Cambridge’s maths lab…
You can listen to the full interview for the Naked Scientists here.
And you can read more about the Navier-Stokes equations and all of the Millennium Problems here.
Grigori Perelman is a quiet and unassuming mathematician from Russia, who took the world of maths by storm in 2010 when he not only solved the Poincare problem but then refused the $1 million reward! I went along to the Millennium Bridge in London to meet mathematician Katie Steckles to shed some light on Perelman’s story and to find out why the Millennium Bridge was in fact its own millennium maths problem…
You can listen to the full interview for the Naked Scientists here.
My first ever live radio interview from July 2015 – enjoy! You can listen to the full interview for the Naked Scientists here.
The Millennium Prize Problems are a set of 7 maths problems that have been deemed so important that if you can solve any of them, you’ll be awarded 1 million Dollars. I was interviewed by Naked Scientist presenter Graihagh Jackson to explain exactly what the problems entail…
If you want to find out more about the Millennium Problems you can find a series of articles I’ve written on the subject here.
I’ve saved the best until last because this one’s been solved! Hallelujah! Praise the Lord! God save the Queen! Slap my thighs and serve me a milkshake! And the story of the man that did it is fascinating. But we’ll get to that… first up I’d better tell you what the problem is/was.
For the Poincare Conjecture we venture into the shape-shifting world of topology. This is a real favourite amongst mathematicians because it’s great for blowing people’s minds. The classic example: in topology a donut and a teacup are the same item. Yes, you did read that correctly. The reason? They both only have one hole: in the centre of the donut and in the centre of the handle of the teacup. It’s the number of holes that’s key. If you have a muffin and a donut how would you tell them apart? And no you can’t eat them. In topology what you would do is take an elastic band and put it around each object. Then you squeeze it in tightly until the object becomes one ball of mass. Well the muffin does, but the donut doesn’t. Not without breaking it at least – that’s the key. The hole in the donut means that you can’t shrink it and squeeze it down into one little ball without breaking it somehow. There’s no way to remove the hole.
If you’re still struggling to get to grips with topology, think of it like this: you have a donut made out of Playdoh and you need to mould it into a teacup with the only rule being that you cannot create or destroy any holes. You can do it. It’s a little fiddly yes, but it can be done. Now imagine you need to make a muffin with the same rule. No hole destroying. You can’t do it. You’ll always be left with a loop of Playdoh hanging off your perfectly crafted muffin.
The Poincare conjecture is based on this same idea: imagine you have a smooth shape made out of Playdoh and it has no holes, then the question is: can we mould it to make a sphere? Sounds easy enough in our three dimensional world, you can literally get a ball of Playdoh and make any shape you want – you can always get back to a sphere. But what happens in higher dimensions? Time is often referred to as the fourth dimension in Physics, but what comes after that? We as humans are not programmed to visualise it, but in maths higher dimensions exist. The interesting thing with this problem is that we know you can make a sphere in any number of dimensions except four and this is what the Poincare Conjecture asks. Can you take any four-dimensional smooth object that doesn’t contain any holes and turn it into a sphere? Turns out you can, just ask Gregori Perelman (photo credit: George M. Bergman – Mathematisches Institut Oberwolfach (MFO), GFDL, https://commons.wikimedia.org/w/index.php?curid=11511619).
Perelman is a Russian mathematician and he is quite the character. He showed that the Poincare Conjecture was true and then without really telling anyone just posted his solution online in 2002. No big event, no announcement, just a casual ‘oh here’s what I’ve been working on the past few years – I solved a Millennium Problem’. You have to love him for it. And it gets better. It took the Clay Institute eight years to verify that his solution was indeed correct and Perelman did not like this, not one bit. He couldn’t understand why they had to check his work – he is a mathematician; he doesn’t make mistakes! When the time came around for him to be presented with his money he declined, flat out turned it down. He was also awarded the maths version of the Nobel Prize, the Field’s Medal, and didn’t want that either. He was so annoyed at the way in which he was treated following his work that he gave up the subject and it is rumoured that he now works in Computer Science. Get your bets in now that he solves the biggest problem in that subject within the next few years…
This is a nice story for me to end on as it brings me back full circle to my starting point for these articles. The Millennium Maths problems were the first set of problems to get me really excited about maths. Whether it was because of the money or just the idea that these things even existed, I don’t know (it was probably the money), but what I do know is that Gregori Perelman is the perfect example of everything that is great about mathematicians. He started working on the Poincare Conjecture in 1995 before it was even a Millennium Problem, and then he turned down all of the fortune and fame that came with his solution. He simply wanted to be left alone to ‘do the maths’.
If after reading my articles you were thinking of attempting to solve one of these problems yourself by all means get stuck in, but as I started with a word of warning about the difficulty of these problems, let me end with another. Estimates of the number of hours spent by Perelman in solving the Poincare Conjecture actually put the $1 million prize money at less than the minimum wage. You have to love the subject to tackle these problems and I hope that I have and will continue to help you do exactly that.
You can listen to me talking to mathematician Katie Steckles about the Poincare Conjecture here.
I’ve written a series of articles on each of the 7 Millennium Problems which can be found here.
The sixth Millennium Problem pretty much sums up why a lot of people don’t like maths. It is by far the hardest to explain in any terms, never mind simple ones, it is incredibly far out of reality and everyday experiences and mathematicians can’t agree on what the actual problem is – never mind how to go about trying to find a solution. I just want to emphasise this last point: depending on which mathematician you ask to define the problem; you will most likely get a different version of what it actually is. The official statement on the Clay Institute website sums it up perfectly: “The answer to this conjecture determines how much of the solution set of a system of algebraic equations can be defined in terms of further algebraic equations.” So if we have a solution to a set of equations, is that solution also the solution to another different set of equations. Solution, solution, solution.
Not to be deterred I will try my best to explain the Hodge conjecture to you – just maybe lower your expectations a little. Instead of that 150-year aged Scotch whiskey you’re used to, on this occasion you might have to settle for a blue WKD (Jamie Vardy would be pleased at least). Before we get to the problem let’s start with the man that proposed it: William Hodge. Hodge was born in Scotland in 1903, he studied at Edinburgh, then Cambridge where he was appointed to a chair position which he held until his death in 1970. He won some awards, including being knighted by the Queen in 1959, and his conjecture was announced in 1950. That’s pretty much it, the full life story. It would be fair to say that we know as much about the man as we do about his conjecture…
I’ve probably stalled long enough, now onto the conjecture itself. In as simple terms as possible, the Hodge conjecture asks whether complicated mathematical things can be built from simpler ones. Not so dissimilar to seeing an entire working city built from Lego and realising that it is in fact all just made from little simple square blocks. Hodge is basically asking whether maths is the same as Lego. The Lego Movie brought the toy back to life so maybe Hollywood should do a Maths Movie to bring the subject into the 21st century. Mila Kunis and Brad Pitt in a race against time to work out the area of a circle before the world blows up… I’d watch it.
To explain the Hodge conjecture in a little more detail I need to give you another quick history lesson. In the first half of the 1900’s mathematicians began to realise that highly complicated mathematical objects could be approximated very well by sticking together smaller and more simple building blocks. The idea being let’s take something we don’t understand and try and build it using something we do. You can imagine the following scenario: an archaeologist realises that his evolution tree is missing a dinosaur – there’s no way the T-rex evolved into a chicken, there must be something in-between. The archaeologist has no idea what this dinosaur looks like, but can start using the information he has about other dinosaurs, for example other fossils and skeletons that were from the same time period to build up a picture of what the missing dinosaur might have looked like…
An artist’s impression:
It’s only a guess and almost certainly isn’t Big Bird, but after more searching and digging for fossils they might find something pretty similar to that guess. This is what mathematicians do. We use what we know to get a better understanding of the things that we don’t know much about.
Now with this idea in mind, we can finally come back to the Hodge conjecture. It asks whether one important class of mathematical objects (called projective algebraic varieties if you must know), which are made up of pieces called Hodge cycles, are in fact themselves made up of smaller pieces called algebraic cycles. In the Lego scenario, the problem is asking whether the Lego blocks making up the city are in fact made up of even smaller and simpler pieces. I did warn you this one gets a little tricky but hopefully now that we’ve got to the end “everything is awesome!!!”
I’ve written a series of articles on each of the 7 Millennium Problems which can be found here.
